Los Angeles area charter schools advocates can now point to a large study by Stanford University researchers to support their claim that the independent schools do a better job of educating students than their public school counterparts, particularly when it comes to low-income Hispanic students in the Los Angeles Unified School District.

Stanford’s Center for Research on Education Outcomes (CREDO) found that overall Los Angeles area charter school students receive the equivalent of 50 more days of learning in reading and 79 more days in math than their peers in traditional public schools.

“Results for Hispanic charter students in Los Angeles, especially Hispanic students in poverty, were noteworthy,” according to Dev Davis, Research Manager and co-author of CREDO’s 2014 Los Angeles Report. “The gains for Hispanic students in poverty at charters amount to 58 additional days of learning in reading and 115 more days in math compared to their district school counterparts,” Davis said.

Stanford researchers followed students for four years, between 2008 and 2012. They received cooperation from the California Department of Education, which according to the report provided researchers access to historical student records, including state achievement testing.

Overall, 48% of charter schools performed significantly better in reading and 44% better in math. Of the 222 charter schools in Los Angeles, 150 had positive growths in reading and math.

The effectiveness of charter schools is a debate that has raged since the schools started appearing two decades ago in Montana, the report notes, but until now there was no hard evidence on the impact charter schools have on student performance.

In both reading and math, charter students in L.A. Unified learned significantly more than their virtual peers in 2010, 2011 and 2012, according to the study. Gains for Hispanic students generally and for those living in poverty also significantly outpaced those of black students who on average only gained 14 days of learning in both math and reading.

The study recorded the progress that a typical Los Angeles charter student would gain in a year of enrollment in a charter school by taking a look at a student’s “virtual twin” or counterpart attending the Traditional Public School (TPS) that they themselves would have otherwise attended based on their address.

CREDO looked at student’s prior academic achievement, race/ethnicity, lunch program participation and special education and English proficiency rates among other categories to match the students up to 93% of the charter students, according to the study.

Compared to traditional public schools, charters have on average about half the number of students enrolled. Of those students, smaller proportions are Asian, Hispanic and students in poverty than at traditional public schools. However, charters in general have larger proportions of black and white students than LAUSD schools in the district, noted the study. Researchers said they factored the differences into their calculations.

Researchers looked at whether charters had an impact on improving education outcomes for students in poverty, analyzing data from 70 percent of charter students eligible for subsidized school meals, an indicator of low-income households.

The study found that students in poverty who are enrolled in Los Angeles charter schools performed significantly better both in reading and in math when compared to students in poverty in traditional public schools.

Despite these gains, black and Hispanic students in charter schools are still performing at a level lower than white students in traditional public schools, but the achievement gap is not as significant for Hispanic students attending charters schools, note researchers.

There were also differences between the gains made at urban and suburban charter schools, with the latter showing more improvement.

English language learners in charter schools also had a higher number of learning days in both reading and math, while there was no significant difference for special education students compared to their peers in traditional public schools.

But not every charter school is doing well, the study found.

Thirteen percent of charter schools have results that are significantly worse than their district school peers in reading, and 22 percent perform worse in math.

Nationally 25 percent of charter schools have significantly larger learning gains in reading, while 29 percent do so in math. Nineteen percent of charter schools have results that are significantly worse than their district school peers in reading, and 31 percent do so in math.

Responding to the study, LAUSD Superintendent said the school district is “very pleased with the results.”

“Today’s study is another indicator of the amazing results our students, educators and parents are accomplishing in Los Angeles.”

The students in both District and charter schools in Los Angeles are achieving at the highest levels in the history of the city, he said.

On the National Assessment of Educational Progress, according to Deasy, LAUSD fourth graders since 2011 had the second-highest overall gain in reading of all 21 urban districts. African-American and white students in fourth grade had the highest gains in reading compared to any other urban districts nationally, and LAUSD had the highest gains in reading scores for eighth graders compared to other districts over the past 10 years, according to Deasy.

“We are excited and further motivated by what the CREDO study highlights as a result of the tremendous work of our students, our charter school partners, our Board of Education and entire District team,” Jose Cole-Gutierrez, Director of LAUSD’s Charter School Division, said.

“LAUSD remains committed to serving with excellence as an authorizer and working in collaboration with our partners so that we learn from one another, ensure quality, and help all students maximize their potential.”